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/*
* dowall.c Write to all users on the system.
*
* Author: Miquel van Smoorenburg, miquels@cistron.nl
*
* Version: @(#)dowall.c 2.85-5 02-Jul-2003 miquels@cistron.nl
*
* This file is part of the sysvinit suite,
* Copyright 1991-2003 Miquel van Smoorenburg.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <stdio.h>
#include <utmp.h>
#include <pwd.h>
#include <fcntl.h>
#include <signal.h>
#include <setjmp.h>
static sigjmp_buf jbuf;
/*
* Alarm handler
*/
/*ARGSUSED*/
static void handler(int arg)
{
siglongjmp(jbuf, 1);
}
/*
* Print a text, escape all characters not in Latin-1.
*/
static void feputs(char *line, FILE *fp)
{
unsigned char *p;
for (p = (unsigned char *)line; *p; p++) {
if (strchr("\t\r\n", *p) ||
(*p >= 32 && *p <= 127) || (*p >= 160)) {
fputc(*p, fp);
} else {
fprintf(fp, "^%c", (*p & 0x1f) + 'A' - 1);
}
}
fflush(fp);
}
static void getuidtty(char **userp, char **ttyp)
{
struct passwd *pwd;
uid_t uid;
char *tty;
static char uidbuf[32];
static char ttynm[32];
static int init = 0;
if (!init) {
uid = getuid();
if ((pwd = getpwuid(uid)) != NULL) {
uidbuf[0] = 0;
strncat(uidbuf, pwd->pw_name, sizeof(uidbuf) - 1);
} else {
sprintf(uidbuf, uid ? "uid %d" : "root", (int)uid);
}
if ((tty = ttyname(0)) != NULL) {
if (strncmp(tty, "/dev/", 5) == 0)
tty += 5;
sprintf(ttynm, "(%.28s) ", tty);
} else
ttynm[0] = 0;
init++;
}
*userp = uidbuf;
*ttyp = ttynm;
}
/*
* Check whether given filename looks like tty device.
*/
static int file_isatty(const char *fname)
{
struct stat st;
int major;
if (stat(fname, &st) < 0)
return 0;
if (st.st_nlink != 1 || !S_ISCHR(st.st_mode))
return 0;
/*
* It would be an impossible task to list all major/minors
* of tty devices here, so we just exclude the obvious
* majors of which just opening has side-effects:
* printers and tapes.
*/
major = major(st.st_dev);
if (major == 1 || major == 2 || major == 6 || major == 9 ||
major == 12 || major == 16 || major == 21 || major == 27 ||
major == 37 || major == 96 || major == 97 || major == 206 ||
major == 230) return 0;
return 1;
}
/*
* Wall function.
*/
void wall(char *text, int fromshutdown, int remote)
{
FILE *tp;
struct sigaction sa;
struct utmp *utmp;
time_t t;
char term[UT_LINESIZE+6];
char line[81];
char *date, *p;
char *user, *tty;
int fd, flags;
/*
* Make sure tp and fd aren't in a register. Some versions
* of gcc clobber those after longjmp (or so I understand).
*/
(void) &tp;
(void) &fd;
getuidtty(&user, &tty);
/* Get the time */
time(&t);
date = ctime(&t);
for(p = date; *p && *p != '\n'; p++)
;
*p = 0;
if (remote) {
snprintf(line, sizeof(line),
"\007\r\nRemote broadcast message (%s):\r\n\r\n",
date);
} else {
snprintf(line, sizeof(line),
"\007\r\nBroadcast message from %s %s(%s):\r\n\r\n",
user, tty, date);
}
/*
* Fork to avoid us hanging in a write()
*/
if (fork() != 0)
return;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = handler;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
sigaction(SIGALRM, &sa, NULL);
setutent();
while ((utmp = getutent()) != NULL) {
if(utmp->ut_type != USER_PROCESS ||
utmp->ut_user[0] == 0) continue;
if (strncmp(utmp->ut_line, "/dev/", 5) == 0) {
term[0] = 0;
strncat(term, utmp->ut_line, UT_LINESIZE);
} else
snprintf(term, sizeof(term), "/dev/%.*s",
UT_LINESIZE, utmp->ut_line);
if (strstr(term, "/../")) continue;
fd = -1;
tp = NULL;
/*
* Open it non-delay
*/
if (sigsetjmp(jbuf, 1) == 0) {
alarm(2);
flags = O_WRONLY|O_NDELAY|O_NOCTTY;
if (file_isatty(term) &&
(fd = open(term, flags)) >= 0) {
if (isatty(fd) &&
(tp = fdopen(fd, "w")) != NULL) {
fputs(line, tp);
feputs(text, tp);
fflush(tp);
}
}
}
alarm(0);
if (fd >= 0) close(fd);
if (tp != NULL) fclose(tp);
}
endutent();
exit(0);
}
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